This invention relates to pumps, more particularly to an expansible chamber pump of a type which may be referred to as a lance pump, particularly adapted for pumping lubricant, including grease, from a supply thereof (e.g. lubricant in a drum).
The pump of this invention is generally in the same field as the pumps shown in the following U.S. patents:
Patent No. Issue Date Title
1. U.S. Pat. No. 2,187,684 Jan. 16, 1940 Lubricating
2. U.S. Pat. No. 2,631,756 Mar. 17, 1953 Apparatus
3. U.S. Pat. No. 2,636,441 Apr. 28, 1953 Lance Type Pump Mounting
4. U.S. Pat. No. 2,787,225 Apr. 2, 1957 Lubricant Pump
5. U.S. Pat. No. 3,469,532 Sep. 30, 1969 Pump
6. U.S. Pat. No. 3,502,029 Mar. 24, 1976 Pumps
7. U.S. Pat. No. 3,945,772 Mar. 23, 1976 Pumps For Transferring Small Quantities Of Dosed Liquids
8. U.S. Pat. No. 4,487,340 Dec. 11, 1984 Adjustable Metering Oil Pump
9. U.S. Pat. No. 4,762,474 Aug. 9, 1988 Pump Having Reciprocating Pipe And Slidably Supported Hollow Body
The pumps shown in items 2, 4 and 5 listed above are identified as lance pumps.
Among the several objects of this invention may be noted the provision of an improved pump generally of the lance pump type especially adapted for operation at relatively high speed, e.g. 600 cycles per minute, in respect to prior pumps of this type; the provision of such a pump especially adapted for more reliable pumping of hard-to-pump grease, including pumping of grease which is thicker because of being subject to low temperature; the provision of such a pump operable with a relatively short pump stroke (e.g. 0.75inches) and with relatively high volumetric efficiency, i.e. higher volume delivery in relation to the size of the pump; the provision of such a pump adapted for operation by a rotary hydraulic motor and especially by a readily commercially available rotary hydraulic motor instead of a special driving means, for cost reduction; the provision of such a pump which is double-acting, i.e. operable to deliver a metered volume of lubricant on an outward stroke as well as an inward stroke; and the provision of such a pump which is especially suitable for use in an automated lubrication system wherein metered charges of lubricant are delivered to different points of lubrication which may require different amounts of lubricant at different time intervals.
In general, a pump of this invention, for pumping a pumpable product, particularly lubricant including grease, from a supply thereof, comprises a head adapted for placement above or at one side of said supply, an elongate member constituting a pump plunger extending outward from the head having an inner end and an outer end, said plunger being fixed at its inner end with respect to the head, an elongate pump tube surrounding the plunger extending out from adjacent the inner end of the plunger to and outside the outer end of the plunger and reciprocable in and out through a pump stroke relative to the plunger, and motor-driven means associated with the head for reciprocating the tube through said pump stroke between an inner position relative to the plunger and an outer position relative to the plunger. The tube has an inner end closure slidable in and out on an inner portion of the plunger adjacent the inner end of the plunger in sealed relation thereto, and an outer closure slidable in and out on an outer portion of the plunger adjacent the outer end of the plunger in sealed relation thereto, closing the tube inside its outer end. The tube is of larger internal cross-section than the cross-section of the plunger throughout the length of the tube between said closures thereby defining an elongate annular pump chamber between the plunger and tube extending from said inner end closure to said outer closure. The tube is open at its outer end and has an inlet check valve adjacent its said open outer end outside the outer end of the plunger defining in conjunction with the outer end of the plunger an expansible and contractible outer end chamber. The cross-sectional area of said inner portion of the plunger is different from the cross-sectional area of said outer portion of the plunger. The inlet check valve opens on an outward stroke of the tube for entry of the pumpable product to said outer end chamber. The pump has a passage for outflow of pumpable product from said elongate annular pump chamber to and through an outlet in the head on an outward stroke and also on an inward stroke of the tube, and further has a passage with a check valve therein adapted to open on each inward stroke of the tube with the inlet check valve closed for delivery of pumpable product from said outer end chamber to said elongate annular pump chamber.
Other objects and features will be in part apparent and in part pointed out hereinafter.